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In their letter, Masin et al. (1) affirm that a “varying extent of contamination” of adenylate cyclase toxin (ACT) and ACT-S606A purified toxin preparations, by the phospholipase A (PLA) enzyme from the outer membrane (OMPLA) of the producing Escherichia coli cells, could easily account for our finding that ACT has intrinsic PLA activity (2). E. coli OMPLA is an integral membrane protein of very low abundance (∼200–500 copies per cell) (3), whose extraction from the bacterial membrane is particularly difficult, requiring harsh detergents (SDS) for its extraction-solubilization (3⇓⇓–6). In …

Researchers report evidence of microbial activity in the hyperarid Atacama Desert and raise the possibility that other harsh environments, such as Mars, may contain microbes similarly adapted to dry conditions.